The answer is straightforward: if you use your balance in anyway, frequent external calibration is very important. This issue frequently arises each time a customer orders a balance and dutifully scans the operator’s handbook, which advises calibration in advance of use.
There are quite a few factors a lab balance needs to be adjusted. The simple process of shipment can cause small shifts to the mechanics of the balance. Some customers could have weights that are slightly different from those used at the manufacturing plant. These types of small differences can mean significant differences in your testing results.
If this balance is relocated to a place where the gravitational pull is higher or less, it can display a different value, as the force will vary. This is what takes place when you navigate around the planet. Gravitational forces isn’t the same everywhere on earth. This is because the earth isn’t a perfect orb. Your location might have a distinct gravitational force compared to the specific location of the manufacturing area producing the balance. Everywhere on the planet is placed differently to “magnetic north.” That means that gravity everywhere will be slightly different, depending upon the distinct location’s elevation in comparison to sea level.
If you stand at either of the Planet’s poles, you’re somewhat closer to the core of our planet than if you stand on the equator. When you move nearer to the middle of the planet earth, the force due to gravity will likely be slightly larger. Once you depart from the center it will be a smaller amount. As a result, in case you climb a mountain peak, you progress farther away from the Globe’s center and the force is less.
Different balances will behave in a different way to a change in location. A less-sensitive balance, for example, one that is readable to one gram, might not be in a position to measure a modification of gravitational forces if it is transferred to another area. More delicate balances, including those seen in a labratory, will more easily show the difference in gravitational forces. For the most sensitive clinical balances, it’s possible that a tiny variation in site may cause significant shifts to the balance’s calibration. As an example an analytical science lab balance capable of analyzing one hundred grams readable to 0.0001 grams can detect very small variations in gravity.
If the balance is adjusted with a one hundred gram test weight and then moved upstairs a couple of floors, the change in gravitational forces can cause the balance to measure the one hundred gram weight as 99.9960 grams, or 0.0040 grams less because it’s farther beyond the middle of the planet. A number of balances are furnished with internal motor-driven calibration, and though it might cost you more, it can be a useful characteristic to include. But nearly all balances with internal calibration also offer external calibration. External calibration is actually a relatively simple process; anybody can do it. It is merely a matter of disciplining yourself to perform this on a frequent schedule.
Art Silverstein has created many reports regarding scale calibration and scale repair in the United States.